The semiconductor integrated circuit (IC) industry has experienced rapid growth in the past several decades. Technological advances in semiconductor materials and design have produced increasingly smaller and more complex circuits. These material and design advances have been made possible as the technologies related to processing and manufacturing have also undergone technical advances. As a size of the smallest component has decreased, numerous challenges have arisen. For example, the need to perform higher resolution lithography patterning grows.
Techniques such as extreme ultraviolet (EUV) lithography have been utilized to support high resolution requirements of nano-scale semiconductor devices. EUV lithography employs radiations in the EUV region, having a wavelength of about 1-100 nm, thereby providing finer resolution than traditional radiation sources such as KrF and ArF. However, realizing all the benefits that EUV lithography can offer remains challenging. One challenge is in the resist materials and the resist patterning processes used for EUV lithography.
A commonly used resist material for lithography is a chemically amplified resist (CAR) that contains backbone polymer protected by acid labile groups (ALGs). CAR further contains photo-acid generators which, upon radiation, produce an acid. The acid can catalyze the cleaving of the ALGs from the backbone polymer, such as in a post exposure bake process. The de-protected portion of the resist is dissolved in a liquid developer, leaving the remaining portion of the resist as a resist pattern. Issues may arise during the exposure and development of the resist. For example, diffusion of the acid during the exposure may lead to blurring of the edges of the patterned areas, thus limiting the resolution and line edge roughness (LER) of the resist pattern. For example, when the exposed resist is developed in a liquid developer, the resist pattern may collapse due to its high aspect ratio and the developer's surface tension.
Accordingly, a new resist and the associated patterning processes are desired.